Spray Foam and Radiant Barrier: How NOT To Do It!!

so why did i completely negate the benefits of my lp tech shield radiant barrier by putting spray foam up against it let's find out today on smith house hey guys make sure you go check out mccopeland.com there's all kinds of great videos over there on how to raise your game as a trades person our goal with mc copeland is to have the best instructors teaching the most up-to-date and technically accurate information which will help take somebody from apprentice who knows nothing about the trades through journeyman all the way through mastery of the subject this is spray foam it is sprayed completely up against a radiant barrier from lp called tech shield it makes the tech shield do nothing there's no reason i should have spent extra money on tech shield so why did i do it well here was my thinking originally i said all right i've got a galvalume roof and then i'm going to put tech shield on and the galvalume roof is going to reflect a lot of the energy and then the energy is going to get converted to conduction and it's going to conduct through the roofing members and then it's going to hit my radiant barrier here in the cavity and it's not going to re-emit and it's going to have to turn around and take a long trip back and re-radiate out into space and it was going to be awesome so i did that i upsized my rafters these are instead of like a two by six these are a full two by ten because with owens corning with a two by ten cavity i can still get an r30 bat with a one inch air gap back behind it and that air gap is critical instead of just being a conditioned space i love conditioned attics because i can keep all of my mechanicals in there my air conditioner runs straight through condition space everybody's happy and then you just reclaim all of the space instead of just being a big empty attic this is actually living space we've got bedrooms and we've got a bathroom and this is just like a family room thing love finished spaces if i wasn't doing this as a finished space this tech shield would be doing its job there would be insulation down here underneath me and the tech shield would not radiate the energy into the attic space and then finally find its way into the cavity below raising the temperature it's going to reject that energy not reflect it's just not going to re-emit it however when you put a material right up against another material you're no longer radiating heat heat transfers in three different ways radiation conduction and convection radiation is how the sun heat gets to the earth right there's nothing there's just space there's a void so it has to go through radiation and then it gets to our atmosphere and it heats up the air and the air flowing around and the water flowing around that's convection that's heat movement through media movement and then there is conduction that's when you have a hot pan and you touch it it's hot ow you touch it it conducts into your skin right those are the three ways so by having a reflective surface on the inside on the inside of an attic space it reduces the material's ability to emit or to radiate the energy into the attic space so that he hits the hits the steel roof it gets turned into a conducted heat and it conducts through the roof membranes and then it can't re-radiate through the foil facing very well so it turns around and it finds its way back out and everybody's happy however in this space i was going to use the owens corning cathedral ceiling bat in this space that would give me that one and a half inch or one inch space back behind the insulation because i can't touch it remember because if i touch it it goes to conduction so i keep that space and then it doesn't re-radiate but any heat that gets in between my insulation and my roof deck is going to find its way out through ridge vents and from eve vents so the air will get heated up and it will flow and it will suck cool air in through my events and it will exhaust through my ridge vent it's a beautiful system vented addicts are awesome however up here if i was going to do that i didn't think about this early on this is you know we're all still learning right um if i was to do that i could have done that that solution would have absolutely worked i put events i put roof vents and we put the air gap and it works however now i am depending on my drywall layer as my air seal layer that means that my water is taken care of by my roof and my wrb on the outside but all of my air has to be sealed from the drywall because i'm intentionally letting air come into this cavity and exhaust out so i have a flow of air i don't like doing that two reasons one it's hard to seal sheetrock it just is you have all of your plugs all around that you've got to do some detailing on you've got all of your lights that you've got to do detailing on you've got your hvac vents that you got to do detangling on everything is a detail and you got to get all that right because you don't want that air getting sucked into your living space especially if it's hot and humid outside and cold inside now you've got condensation and you've got condensation around all your hvac vents and everything's moldy and nobody's happy i don't like doing it two even if you get all those details right because you're a great builder and you know how to do it and you detail it and it's all perfect what happens in 10 years when new owners come in i'm like you know what i'd like to do i like to put a light right there they drill a hole they hang a light you've just popped your balloon you have this awesome detailed drywall balloon that was keeping all the bad air out and all the good air in they just popped it and they have no idea that they just popped it no idea nobody thinks nobody thinks about putting in a light and thinking well what did i just do to the air ceiling in this home nobody guarantee you ask a hundred homeowners and a hundred of them would be like i wanted a light there right so i don't like air sealing off the drywall and that's what i was going to be forced to do if i kept going down the path that i was going so then i thought well can i still use the insulation the the fiberglass insulation and have the gap and just you know sort of leave out leave out the ridge vents and the events and that whole i still have my air gap and yeah it'll get super heated in there but it's the honest answer is i don't know what would happen i don't part of me can argue well it would be a closed system in there and you would have micro currents that would get heated up and then go up and then come back down but because you're completely sealed you're not going from the outside you're not letting moist air in so it should be fine because it's just but i felt like i was getting too far over my skis i felt like i was getting out from the we know this works to the hey jordan's going to try something and it's never good when you're building houses for other people to be in that jordan's going to try something i love trying stuff i try stuff all the time i try stuff on my house where i can watch it for a while and see how it's going to work i don't try stuff on other people's houses and that's when i took a step back and said you know what i'm i'm not comfortable with putting the ridge vents and events in and i'm also not comfortable doing the hybrid system i know that i can spray foam the deck straight up against the radiant barrier and i also know that that completely negates any of the benefits of having the radiant barrier up there i'm going to take the lumps i'm going to swallow my pride i'm going to spend the money on the tech shield that's doing zero good and i'm going to spray foam it and that's what i did so i have got well over r30 of spray foam up here slightly closer to r38 or something up here because i have such big rafters up here um everything's air sealed with my spray foam actually everything it was already air sealed with my wrb this is lp weather logic on the outside and that's where i'm getting my air ceiling from and i'm doing details up around the house so i'm not depending on the the spray foam too much but every little bit helps right so we're we're very tight in this house we haven't done a blower door on it yet but i'm expecting sub 1 sub 1 ach 50. um but at the end of the day the tech shield is doing zero good and that's sort of a disappointment because i was looking forward to having like all the cool bells and whistles check so the moral of the story is twofold number one never be too proud to say you know what i was thinking i was going to do might not be the best solution maybe i should do a proven concept even if it cost me a little bit more money and then that leads to number two never be afraid to spend a little bit more money doing it the right way like once you know like okay that's the right thing to do would have been very tempting for me to spend less on fiberglass because that's way cheaper than spray foam and i had already spent the money on the tech shield so this is like this solution here is the most expensive option that there was but it's the right thing to do and the owners of this house are going to be living in here for a very long time this house will be here long after i'm dead and i'm not building for me i'm building for the future so yeah it i don't make as much money on this i guarantee you i'm going to think a little bit more about it in the future about like okay am i doing this way or am i doing that way and which way am i most comfortable with so i don't waste money in between time trying to do a hybrid system but i'm always going to do the right thing to make sure that the home is best served for functionality durability and beauty thanks so much for watching i hope you learned something here i hope that answers some of the questions that you'll had about like why i thought you were doing tech shield why is there spray foam up against there because i know that's what a lot of you were thinking comment below any other questions that you might have on this comment below do you love spray foam do you hate spray foam what's your favorite type of insulation what are your opinions on radiant barrier and how can i show people that the science behind radiant barrier not whether it's worth the money or not not that science i'm just saying the science of radiant barriers and emissivity being a thing how can i show people that very convincingly because i haven't done it well yet comment that below would love to hear your ideas thanks so much for watching go check us out at mt.copland at instagram at smithhouseco and at jordan smith builds and we'll see you next time on smith house [Music] [Music] you

Channel: Jordan Smith

Views: 74,208

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Id: oIcGJ_OFVc4

Length: 11min 49sec (709 seconds)

Published: Fri Nov 06 2020